Apparently there are newer synthetic hairs that are more heat resistant, but there are lots of online horror stories of opening an oven door and the blast of heat melting all the hairs!

I'd just like to point out than not all donated human hair is sold on by religious bandits purely for self gain profit.

The hair is donated to the religion as an offering, a centuries old tradition, and the money raised through selling it on is used to help & feed the poorer members of that religion.

I'm sure as a system its open to abuse, but still, the intention is honourable & noble.